Date:   Wed, 25 Jan 2023 10:29:24 +0700
From:   Ammar Faizi <ammarfaizi2@gnuweeb.org>
To:     "H. Peter Anvin" <hpa@zytor.com>
Cc:     x86 Mailing List <x86@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Xin Li <xin3.li@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Cooper <Andrew.Cooper3@citrix.com>,
        Brian Gerst <brgerst@gmail.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Shuah Khan <shuah@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Linux Kselftest Mailing List 
        <linux-kselftest@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v3 2/2] selftests/x86: sysret_rip: Add more syscall
 tests with respect to `%rcx` and `%r11`
Message-ID: <Y9CiFEoiLislQZCx@biznet-home.integral.gnuweeb.org>
References: <5ecc383c-621b-57d9-7f6d-d63496fca3b3@zytor.com>
 <20230124022729.596997-1-ammarfaizi2@gnuweeb.org>
 <20230124022729.596997-3-ammarfaizi2@gnuweeb.org>
 <ce25e53f-91d4-d793-42a5-036d6bce0b4c@zytor.com>
 <Y899kHYbz32H1S6a@biznet-home.integral.gnuweeb.org>
 <BC632CA8-D2CB-4781-82E5-9810347293B0@zytor.com>
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 <20230124100926.637335-1-ammarfaizi2@gnuweeb.org>
 <20230124100926.637335-3-ammarfaizi2@gnuweeb.org>
 <48072ce2-e28d-9267-1f8e-3c76682fb782@zytor.com>
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On Tue, Jan 24, 2023 at 12:59:23PM -0800, H. Peter Anvin wrote:
> 
> 
> On 1/24/23 02:09, Ammar Faizi wrote:
> > From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
> > 
> > Test that:
> > 
> >   - "syscall" in a FRED system doesn't clobber %rcx and %r11.
> >   - "syscall" in a non-FRED system sets %rcx=%rip and %r11=%rflags.
> > 
> > Test them out with a trivial system call like __NR_getppid and friends
> > which are extremely likely to return with SYSRET on an IDT system.
> > 
> > Link: https://lore.kernel.org/lkml/25b96960-a07e-a952-5c23-786b55054126@zytor.com
> > Co-developed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
> 
> Add to the description that the purpose of this is to ensure that various
> system calls are *consistent*, as per the comment immediately below your
> code.

Added in v4.

-- 
Ammar Faizi